The invention relates to improvements in rolls and in systems of rolls for use in calenders (including supercalenders) and like machines for the treatment of running webs of paper, textile, metal or plastic material. More particularly, the invention relates to improvements in systems of rolls wherein at least one roll has a deformable hollow cylindrical shell which surrounds and is movable radially and can rotate relative to a stationary carrier, and wherein selected portions of the shell can be deformed by one or more rows of supporting elements serving to regulate the width of the nip of the shell with an adjacent roll as well as the force which is applied to selected portions of the running web. Still more particularly, the invention relates to improvements in systems of rolls wherein the end portions of the shell of at least one roll surround and are rotatable relative to as well as movable radially with annular members in the form of rings or the like.
Commonly owned German Offenlegungsschrift No. 33 25 385 discloses a system of rolls wherein at least one roll is constructed and assembled in the above outlined manner. The means for actually supporting the shell of the one roll includes rows of primary and secondary hydrostatic supporting elements which react against the carrier and have exposed surfaces indirectly acting against the internal surface of the shell with the interposition of films of a fluid medium. The end portions of the shell are free to move radially with reference to the adjacent portions of the carrier. The purpose of annular members in the end portions of the shell is to carry seals which cooperate with sealing rings on the carrier. The profile of the shell can be regulated by appropriate selection of pressures which are applied to the supporting elements by hydraulic cylinder and piston units to ensure that the width of the nip will match a desired value and that the pressure which is applied to the web running through the nip will be distributed in a preselected way. When the shell is in a state of equilibrium, the sum of forces which are transmitted thereto by the load plus the secondary supporting elements matches the sum of forces which are applied by the primary supporting elements.
A modified roll for use in systems of rolls for calenders or the like is disclosed in commonly owned German Offenlegungsschrift No. 34 16 210. The main difference between the roll which is disclosed in this publication and the previously discussed roll is that the roll of the Offenlegungsschrift No. 34 16 210 comprises ring-shaped annular members which are disposed at the ends of the shell and are held against any movement relative to the carrier, i.e., the end portions of the shell are also held against any movement with reference to the respective end portions of the carrier. This is desirable and advantageous in certain types of machines wherein the axes of the end portions of the shell should, or must, be maintained at a fixed distance from the axis of the carrier. Moreover, this renders it possible to accurately locate the ends of a nip which is defined by the shell with a neighboring roll of the system. However, rigid mounting of the end portions of the shell often interferes with, or actually prevents, the shifting of the shell to an optimum position by way of the supporting elements which are confined in the shell and react against the carrier. This will be readily appreciated since the supporting elements can influence only that part of the shell which is located between the fixedly mounted annular members, i.e., only the intermediate portion of the shell.
Further conventional rolls are disclosed in German Offenlegungsschrift No. 30 49 080 of Schiel et al. and in German Auslegeschrift No. 28 26 316 of Biondetti et al.